Just a matter of weeks from now, on December 31, as millions of Americans don party hats and pop champagne corks to usher in the New Year, Kathleen Casey, the Philadelphia-born daughter of a Navy machinist and his wife, will likely find her phone once again ringing off the hook. It happens every decade or so. Journalists and academics and earnest civic leaders, family and friends, all find their way to Casey’s doorstep, hoping for just a few minutes of her time, eager to glean a little bit of wisdom about what it all means and where it’s all going.

Kathleen Casey, you see, bears the unique distinction of having launched the baby boom.

Born at 12:01 a.m. on January 1, 1946, she was the first of 76 million Americans brought into the world between 1946 and 1964, when, in a sharp reversal of a steady century-long decline, the national birthrate skyrocketed, creating a massive demographic upheaval.

So this year the very first baby boomer, the vanguard of that endlessly youthful generation, turns 60. But hers is not like other generations. If its last, unrecorded member was born at 11:59 p.m. on December 31, 1964, he or she will just be turning 41. Certainly this person, the Unknown Boomer, will have encountered very different cultural signposts than did Kathleen Casey (say, Pat Boone vs. the Sex Pistols), but together the two of them bracket a group that, despite its immensity, is strangely unified, and whose influence today defines both the limits and the promise of American life—and will for years to come.

Last summer, 40 years after “(I Can’t Get No) Satisfaction” climbed to the top of Billboard ’s singles chart and earned the Rolling Stones their first gold release in the United States, the Stones launched their 2005 World Tour at Boston’s Fenway Park. For tens of thousands of boomers who came to see Mick Jagger and Keith Richards perform the greatest hits of yesteryear, age really is just a number.

Their kids might have been mortified to see these graying veterans of the 1960s filling a ballpark for one last great rock ’n’ roll show. But in many ways, it all makes sense. There is still no more fitting anthem for the baby-boom generation than the Stones’ signature hit.

Raised in an era of unprecedented affluence and national omnipotence, but coming of age in a time that perceived more limited resources and diminished American power, the boomers have long been defined by a vain search for satisfaction. No matter how much they have, they can’t ever seem to get enough. This quest for satisfaction has at times led to nadirs of narcissism and greed. As a generation the boomers have always seemed to want it all: cheap energy, consumer plenty, low taxes, loads of government entitlements, ageless beauty, and an ever-rising standard of living. They inherited a nation flush with resources and will bequeath their children a country mired in debt.

But their quest for personal satisfaction has also pushed the boundaries of civic life in radical and unusual directions. In their youth, black and white boomers took to the streets to tear down the walls of racial segregation. They strove toward greater equality of opportunity between men and women, made it harder for policymakers to choose war over peace without first convincing a skeptical electorate of its merits, and created a nation that was more accepting of diversity.

For all their faults and all their virtues, they remain exemplars of what Henry Luce called the American Century. The social commentators Neil Howe and William Strauss got it exactly right when they wrote that “from V-J Day forward, whatever age bracket Boomers have occupied has been the cultural and spiritual focal point for American society as a whole. Through their childhood, America was child-obsessed; in their youth, youth-obsessed; in their ‘yuppie’ phase, yuppie-obsessed.” Maybe Luce had it wrong. It wasn’t the American Century. It was the Boomer Century.

The boomers, said one critic, were a distinctive “tribe with its roots in time, rather than place or race.”

Scholars continue to marvel at the phenomenon known as the baby boom. It seemed then, and seems now, to fly in the face of modern demographic and social history. Between 1800 and 1920 the number of children borne by the average American woman fell by more than half, from roughly seven to three. As America transformed itself from a nation of small farmers into an urban, industrial behemoth, increasing numbers of parents no longer needed small armies of children to work the family farm. In this new world of machine and factory, surplus children were a liability. They required much in the way of food, clothing, and shelter but contributed very little in turn to the economic well-being of their families.

The national birthrate, long on the decline, bottomed out in the 1930s. With unemployment running as high as 25 percent, many young Americans, facing an uncertain economic future, decided to put off marriage and parenthood until better days.

When those better days finally arrived in 1940, courtesy of America’s swift and total mobilization for war, most commentators expected only a temporary upsurge in births. The editors of Life magazine worried that by 1970 the Soviet Union’s population would outstrip that of the United States, Britain, France, and Italy combined. They were taken completely by surprise at the magnitude and duration of what actually followed.

Beginning in 1942 with so-called furlough babies, taking off in May 1946—nine months after V-J Day—and peaking around 1947 or 1948, when an American child was born every eight seconds, the GI generation broke sharply with a century-long demographic trend toward smaller families. The population boom also hit Australia, Canada, and New Zealand, whose economies enjoyed a postwar expansion similar to (though not on scale with) America’s, but not Europe, large portions of which lay in ruins. Little wonder, then, that a British visitor traveling in the United States in 1958 observed with something like amazement that “every other young housewife I see is pregnant.”

Though its causes continue to puzzle scholars, the baby boom probably grew from three distinct trends.

First, in the prosperous 1940s and 1950s, thirtyish Americans who had postponed marriage and children during the Great Depression were eager to make up for lost time and start building families. They crowded the field 10 years after they would normally have contributed their share of progeny to the national population.

Second, they were joined by a younger cohort, including many recently demobilized GIs who had come home to find economic prosperity, generous government assistance in the form of housing and educational benefits for veterans, and a general sense of optimism born of conquering global fascism. For these young victors, many still in their early twenties, it made little sense to put off marriage and family. Like their older brothers and sisters, they understood that the years of Depression scarcity and wartime sacrifice were over.

Finally, and in a more subtle way, the general euphoria that drove up marriage and birth rates was soon complemented by Cold War–era anxieties over nuclear competition. In an uncertain world, the comforts of home and hearth could provide a salve against atomic angst, just as the stabilizing influence of marriage and parenthood offered a strategic advantage in the nation’s struggle against communism.

Noting the dangers posed by the Cold War, two Harvard sociologists informed the Ford Foundation that the “world is like a volcano that breaks out repeatedly… . The world approaches this critical period with a grave disruption of the family system… . The new age demands a stronger, more resolute and better equipped individual… . To produce such persons will demand a reorganization of the present family system and the building of one that is stronger emotionally and morally.” Ultimately, if Americans wanted to do their part in this new global war, they’d settle down, have lots of kids, and raise them to do well in school and well in life.

Even household architecture seemed to reinforce the relationship between Cold War worries and the cult of domesticity in which the baby boom prospered. The standard suburban ranch house favored by many young families in the 1950s was set back from the street and protected by a fence, and it had a low-slung roof and an attached carport, lending it a bit of the appearance of a well-fortified bunker.

Not just homes, but the children who were starting to crawl through them, formed a “defense—an impregnable bulwark” against the horrors of the atomic age, the social commentator Louisa Randall Church argued in 1946. Many Americans seemed to agree, and out of this vague combination of economic optimism and atomic unease, they were fruitful, and they multiplied.

Relatively speaking, to grow up a middle-class American child in the 1950s meant wanting for nothing.

Their children—the boomers—were necessarily a heterogeneous lot. America still suffered from deep racial and economic divisions. A country as large as the United States contained a host of distinctive regional folkways. Still, as the cultural critic Annie Gottlieb has observed, for all their differences, the baby boomers formed a distinctive “tribe with its roots in time, rather than place or race.” By any measure, the America in which they grew up was more abundant, more powerful, and more enraptured with its own glory than ever before. When John F. Kennedy called on his countrymen to “explore the stars, conquer the deserts, eradicate disease, tap the ocean depths, and encourage the arts and commerce,” he echoed the optimism that helped forge the new generation’s outlook.

Part of this confidence grew out of America’s total victory in World War II and the country’s scientific and medical achievements, including Jonas Salk’s discovery of a polio vaccine in the early 1950s. But most of it was due to the nation’s dynamic economy. Between 1940 and 1960 our gross national product doubled; real wages—and real purchasing power—increased by 30 percent; the portion of owner-occupied homes climbed to 61 percent; four-fifths of American families kept at least one car in the driveway; average life expectancy rose by almost 11 percent; most employees of large firms enjoyed such new benefits as private health insurance, paid vacations, and retirement pensions; and the typical American house held seven times more gadgets and goods than in the 1920s. By 1957 the energy of the American economy led U.S. News & World Report to declare that “never had so many people, anywhere, been so well off.” When Richard Nixon famously sparred with Nikita Khrushchev at the 1959 American National Exhibition in Moscow and proclaimed the superiority of the American suburban kitchen, with its sleek electric appliances in their myriad styles and models, he articulated a vague but popular sense that America’s consumer abundance was a sure sign of its Cold War advantage.

For boomer children, this cornucopia translated into billions of dollars’ worth of Hula-Hoops, Davy Crockett raccoon-skin hats, Hopalong Cassidy six-shooters, bicycles and tricycles, Slinkys, Silly Putty, and skateboards (and, in California, the shining lure of Disneyland). The writer Joyce Maynard remembered that when the Barbie doll made its debut in 1959, her world changed “like a cloudburst, without preparation. Barbie wasn’t just a toy, but a way of living that moved us suddenly from tea parties to dates with Ken at the soda shoppe.” Relatively speaking, to grow up a middleclass American kid in the 1950s meant wanting for nothing.

It also meant television. in just four years, between 1948 and 1952, the number of American households with TV sets jumped from 172,000 to 15.3 million. T. S. Eliot observed that television was “a medium of entertainment which permits millions of people to listen to the same joke at the same time, and yet remain lonesome,” but for the millions of children raised on it, the new device offered up endless hours of entertainment in the form of family sitcoms like “The Adventures of Ozzie and Harriet,” “Father Knows Best,” and “Leave It to Beaver,” all of which idealized the carefree, child-centered world of suburban America.

More popular still were the Westerns: “Gunsmoke,” “Wyatt Earp,” “Bonanza,” “The Texan,” “Wagon Train,” “Cheyenne,” “The Rifleman,” “The Outcasts,” “Wanted: Dead or Alive,” “Have Gun, Will Travel.” Together, these serial epics captured close to half of America’s weekly television audience and, by the end of the decade, constituted 7 of the 11 most popular shows on the small screen. The programs mythologized the rugged individualism and physical strength of the American frontiersman, who tamed both his enemy (the Indian or outlaw standing in for the Soviet menace) and the natural environment. It was a genre well suited for a country confident of its ability to reach the stars, vanquish disease, and collapse the limits of time and space.

Complementing this message of abundance and conquest were new vogues in child rearing and pedagogy rooted in John Dewey’s ideas about the merits of progressive education. They entered the mainstream in 1946, when Benjamin Spock published The Common Sense Book of Baby and Child Care . His book instructed the parents of the baby-boom generation to go light on punishment and heavy on reason and persuasion, and to bear in mind that their daughters’ and sons’ happiness was the paramount objective of child rearing. If Johnny steals someone’s toy, don’t hit him. Explain that stealing is wrong, and buy him the toy that he coveted. If Suzie misbehaves at the dinner table, don’t worry. Table manners are overrated.

Spock was enormously influential. A study conducted in 1961 revealed that two-thirds of new mothers surveyed had read his book. He made permissive or child-centered parenting mandatory for millions of new postwar middle-class families. By the mid-1950s his message was routinely echoed in the pages of Parents magazine and found confirmation in countless sociological studies.

A 1961 study revealed that two-thirds of all new mothers surveyed had read Dr. Spock.

In later years critics would decry the effects of progressive child rearing, some of them crediting it with an entire generation’s egotism. The iconoclastic historian Richard Hofstadter worried that America would be overrun by the “overvalued child.” Writing of the typical GI generation mother, the novelist Lisa Alther lamented: “If anything had been drummed into her in years of motherhood, it was that you mustn’t squelch the young. It might squelch their precious development. Never mind about your own development.”

Hyperbole aside, millions of boomers did grow up in prosperous, nurturing homes in which children formed the core of the family. Raised amid plenty, taught to value their needs and satisfy their wants, and imbued with a sense of national greatness and purpose, it would have been odd had they not entered young adulthood with at least some sense of entitlement.

In 1956, noting the connection between post-war vogues in Freudian analysis and progressive child rearing, the literary critic Alfred Kazin was bemused by the national “insistence on individual fulfillment, satisfaction and happiness.” Years later the pollster Daniel Yankelovich observed that grown boomers, instead of asking themselves, “Will I be able to make a living?,” as their parents, raised in the Depression years, often did, were more prone to wonder, “How can I find self-fulfillment?”

No american generation has been so intensely studied, so widely celebrated, and so roundly condemned as this one. Out of the cacophony of analysis, two standard criticisms—one from the left, the other from the right—stand out.

For contemporary liberals, popular films like The Big Chill and television series like “thirtysomething” follow a familiar narrative line in which idealistic, socially committed children of the sixties grow into self-centered, blandly acquisitive adults. In the words of the former sixties activist Todd Gitlin, by the 1980s a generation that once raged against “banality, irrelevance, and all the ugliness which conspire to dwarf or extinguish the human personality” had graduated from “ J’accuse to Jacuzzi.”

Even when television boomers retained their fundamental goodness—think, for instance, of Michael J. Fox’s parents, Elise and Steven Keaton, in the popular 1980s sitcom “Family Ties”—they remained painfully conscious of their generation’s potential drift toward self-absorption.

To conservatives, on the other hand, the generation embodies the evils of secular liberalism. In Slouching Towards Gomorrah , Robert Bork credits the pampered baby-boom generation with virtually every insidious social trend in recent American history. “The dual forces of radical egalitarianism … and radical individualism (the drastic reduction of limits to personal gratification),” explains the book’s back cover, have “undermined our culture, our intellect, and our morality.”

Of course, traditionalists don’t have to look far to make their case. Boomers are certainly more tolerant than their parents of looser personal mores. In 1983, 44 percent of them approved of cohabitation outside marriage, 29 percent supported legalizing marijuana, and 37 percent endorsed casual sex. Whereas only a quarter of Americans approved of premarital sex in the 1950s, by the 1970s that figure had climbed to three-quarters.

More recently, boomers from left and right have begun weaving a third critique. In an effort of historical revision that comes close to self-flagellation, they have begun to worship their parents’ generation. That the “GI Generation” has become “the Greatest Generation” is evident everywhere—in popular television series like “Band of Brothers,” in films like Saving Private Ryan , and in official tributes, such as the World War II memorial in Washington, D.C. Offered by the children of G.I. Joe and Rosie the Riveter, these accolades carry an implicit message: Try as we may, we will simply never measure up to our parents’ self-sacrificing greatness.

The problem with all these critiques is that they ignore both the creative use to which the generation has sometimes put its terrific sense of entitlement and the continuities between sixties idealism and eighties excess.

These students ultimately compelled the nation to confront inequities “the Greatest Generation” hadn’t.

In February 1960, when four black college students staged a sit-in at a Woolworth’s lunch counter in Greensboro, North Carolina, sparking a national campaign and inaugurating a decade of youth-driven political activism, they were doing nothing so much as demanding access to the same entitlements that other children of the postwar era claimed as their American birthright. A sympathetic advertisement appearing in three Atlanta newspapers in March 1960 hit the nail on the head when it explained “the meaning of the sit-down protests that are sweeping this nation”: “Today’s youth will not sit by submissively, while being denied all of the rights, privileges, and joys of life.” Raised on the same television advertisements and political rhetoric as their white peers, young black Americans were determined to get their piece of satisfaction.

In a country where happiness and dignity were so inextricably bound up with the individual’s right to enjoy the blessings of the national wealth, this argument resonated. In his “Letter from Birmingham Jail,” Martin Luther King, Jr., the father of young baby boomers of his own, drove home this point. He spoke of finding your “tongue twisted and your speech stammering as you seek to explain to your six-year-old daughter why she can’t go to the public amusement park that has just been advertised on television, and see tears welling up in her eyes when she is told that Funtown is closed to colored children.”

The legions of junior high and high school students who heeded his call in Birmingham—who filled the jails, attended the prayer meetings, and drove King himself to embrace more radical tactics and demands—ultimately compelled the nation to confront long-standing inequities that “the Greatest Generation” had been content to ignore.

They were the shock troops of the 1960s rights revolution. Like their white peers, these boomer kids had seen an average of 500 hours of television advertisements by the age of 6 and over 300,000 commercials by the age of 21. (King’s daughter had clearly seen an ad for Funtown.)

In the aftermath of the Newark riots of 1967, the black poet Amiri Baraka told a state investigatory commission that the “poorest black man in Newark, in America, knows how white people live. We have television sets; we see movies. We see the fantasy and the reality of white America every day.” The schism between fantasy and reality could inspire a truly creative tension.

And so it went for other boomers as well. Young black activists influenced women, gays and lesbians, students, welfare recipients, Latinos, and American Indians to appreciate the gap between America’s lofty democratic promise and its imperfect reality, and to work to narrow that gap.

By the 1970s boomer rights activists forced changes in credit laws, so that married women could have their own credit cards, and pushed for the enactment of Title IX, which broke down gender barriers in education and athletics. In forcing a new liberalization of sex and romance, they insisted on everyone’s right to satisfaction and self-realization—not just married couples but also unmarried partners, no matter what their sexual orientation. They played an instrumental role in bringing down a U.S. President, Lyndon Johnson, and in making the Vietnam War increasingly untenable for his successor, Richard Nixon.

In other words, the generation raised on Spock, television, and abundance put its sense of privilege and entitlement to work for the better good. Today most scholars agree that the boomers will leave their children and grandchildren a country that’s a little more just, a little more humane, and a little more inclusive than the one they inherited from their parents.

The antiwar movement was always more self-interested than its veterans might wish to admit.

These accomplishments notwithstanding, it’s small wonder that the generation has accumulated mixed reviews. The radical left is no happier with the boomers than is the reactionary right. In their youth they effected so massive an upheaval in politics and culture that they were bound eventually to fall in the public’s esteem. Apostles of what Gitlin has called “the voyage to the interior,” and what the late historian and social critic Christopher Lasch derided as a “culture of narcissism,” they seemed after the 1960s to place an unusually high premium on self-discovery and personal satisfaction.

The generation that had raged against authority, vowing with Bob Dylan, “I ain’t gonna work on Maggie’s farm no more,” was now swinging to Andrea True’s refrain “More, more, more. How do you like it, how do you like it?” They bought minivans, microwaves, and self-help books, embraced transcendental meditation, embarked on various diets, visited tanning salons and fat farms, and filled their homes with more durable goods than their prosperous parents could ever have imagined.

Even their politics seemed to change. In 1980 it was an eleventh-hour swing among boomer voters that turned Ronald Reagan’s razor-thin margin into a landslide victory. In fact, there was always more continuity than the critics liked to admit. Even in 1972, the first year that 18-year-olds were allowed to take part in national elections, fewer than half the eligible new voters bothered to show up at the polls, and just half of those who did cast their lot with the liberal antiwar Democrat George McGovern.

Popular memory notwithstanding, the sixties generation has never been a political monolith. Nor was it uniformly engaged by public issues. Only 20 percent of students who attended college in the late 1960s participated in marches or protests, and far fewer—2 or 3 percent—regarded themselves as activists.

The antiwar movement, which many liberal boomers fondly remember as embodying the altruistic, public spirit of the era, was always more self-interested than its veterans might wish to admit. Whereas virtually every able-bodied, draft-eligible man of the GI generation served in the military during World War II, only 10 percent of the 27 million draft-eligible boomers were in uniform while America fought the Vietnam War. The rest, most of them white and middle-class, found creative ways to stay safe. They claimed medical dispensations and student deferments, became schoolteachers or entered defense industries, or married and had children before their local draft boards could sweep them up.

In opposing the war, which many activists did sincerely view as both immoral and unwinnable, protesters betrayed as much selfish entitlement as noble intent. They wanted the United States out of Southeast Asia, but they also wanted to keep themselves out of Southeast Asia. Richard Nixon understood this when he shifted the draft burden away from men in their twenties and back onto 18and 19-year-olds. Suddenly college campuses quieted down. Why bother to protest once you’re safely out of the woods?

In effect, for all their racial, economic, and cultural diversity, if the boomers shared anything, it was that perpetual search for satisfaction. In their best moments, and in their worst, they demanded that the country make good on the promises it had handed them in the 1950s. The problem was that when they began to come of age in the 1970s, the bottom fell out on the American economy. Even as they clamored for “more, more, more,” what they found was less, less, less. Between the 1960s and 1980s the income of young men just entering the job market declined by 50 percent. This mostly was due to forces beyond anyone’s control: Government expenditures for the Vietnam War caused runaway inflation; economic restructuring took a toll on manufacturing; oil shortages in the 1970s drove up energy costs and interest rates. The long slump also came from the gradual erosion of progressive tax policies and growth in entitlements like health insurance.

Ironically, the baby boom was itself a major cause of the nation’s economic slide. So many young people seeking jobs drove down wages and accounted for as much as half of the unemployment rate during the 1970s and 1980s. So boomers made the necessary adjustments. To maintain a standard of living that reflected their upbringing, they, like their Depressionbred parents, postponed marriage and children. Though women’s wages, once adjusted for changing education and skill levels, remained stagnant in the 1970s and 1980s, the proportion of young married women in the work force more than doubled, from roughly 30 percent to 70 percent. Two-earner households helped keep pace with the generation’s material expectations, but at the expense of outsourcing Generation X to after-school daycare and sports programs.

They will continue to do what they have done since 1946—stretch the limits of America’s possibilities

Even these adjustments fell short. The generation that couldn’t get no satisfaction could hardly be expected to live within its means. In 2002 baby boomers spent between 20 percent and 30 percent more money each year than did the average American consumer. In part, this was out of necessity. They had children to feed, houses to furnish, and college tuitions to pay. But the boomers have long stretched the limits of sound household economy. According to the economist Robert Samuelson, between 1946 and 2002 consumer debt climbed from 22 percent of household income to 110 percent. In other words, we’ve become a debtor nation, and the boomers have presided over this transition.

Now at the height of their political influence (the 2000 presidential election saw the first-ever race between two baby boomers, and the commentators Neil Howe and William Strauss estimate that boomers will hold a plurality in Congress until 2015) they are also presiding over the creation of a national debt that their children and grandchildren will be left to pay off in coming years.

In the end the boomers may be less culpable, less praiseworthy, and less remarkable than they, and everyone else, think. Their cohort was so big, arrived so suddenly, and has grown up so closely alongside the modern broadcast media that they have always struck us as standing apart from larger historical forces that drive the normal workings of states and societies. Yet much about this seeming exceptionalism just isn’t new.

When the husband-and-wife sociologist team Robert and Helen Lynd visited Muncie, Indiana, in the early 1920s, they found many of the same traits popularly associated with the boomers already evident among Jazz Age youth. Their famous, pathbreaking book, Middletown: A Study in Modern American Culture , reported a younger generation in the thrall of movies and music, willing to stretch the limits of romantic and sexual propriety, obsessed with clothes and cosmetics, and eager to stake out shocking new degrees of personal autonomy.

And if the children of the 1950s were technically the first generation raised on Spock, they weren’t the first generation raised on the ideas of Spock. By the mid-1930s upward of 75 percent of middle-class men and women were reading advice books that, more often than not, counseled unprecedented attention to the child. Most experts in the 1920s and 1930s had figured out Spock before Spock figured out Spock.

Nor were the boomers the first generation to make therapeutic self-discovery a competitive sport. In their parents’ youth, in the twenties and thirties, Freud was already all the rage. Popular books of the day included The Psychology of Golf , Psychology of the Poet Shelley , and The Psychology of Selling Life Insurance . Bookstores and mail-order houses peddled new titles like Psychoanalysis by Mail , Psychoanalysis Self-Applied , Ten Thousand Dreams Interpreted , and Sex Problems Solved .

Long before the boomers arrived on the scene, Americans were drawn to a new cult of self-improvement that celebrated the mastery of one’s deepest impulses and thoughts. In the 1920s millions followed the advice of the French wonder guru, Emile Coué, faithfully repeating the simple catechism “Day by day, in every way, I am getting better and better.” The explosion of self-help literature peaked in 1936 with the publication of Dale Carnegie’s How to Win Friends and Influence People .

If the boomers weren’t entirely original in their loosened sexual standards, emphasis on physical appearance and youth, or search for a therapeutic mind cure, neither were they all that unusual in their resistance to collective sacrifice. It hardly diminishes the decisive effort of the World War II generation to note that civilians traded on the black market, deeply resented rationing and wage and labor controls, and often worked in defense production as much for profit as for patriotism.

Even the era’s soldiers had mixed reasons for going to war. When The Saturday Evening Post ran a series of articles by American GIs entitled “What I Am Fighting For,” readers learned that their sons and brothers were in Europe “for that big house with the bright green roof and the big front lawn,” their “nice little roadster,” pianos, tennis courts, and “the girl with the large brown eyes and the reddish tinge in her hair, that girl who is away at college right now, preparing herself for her part in the future of America and Christianity.”

The same conflation of private and public interests drove home-front advertisers to pitch their wares as a just reward for wartime sacrifice—as in an ad promising that “when our boys come home … among the finer things of life they will find ready to enjoy will be Johnston and Murphy shoes. Quality unchanged.”

None of this suggests that the boomers aren’t a distinct category of Americans. If many of the character traits popularly assigned them were in evidence long before they were born—if the boomers were, in fact, walking along the arc of history rather than outside it—still, they have, for good and for ill, made a lasting imprint on the nation.

Social commentators have long been inclined to make sense of the world in generational terms. Writing about his travels in the United States in the 1830s, Alexis de Tocqueville argued that “among democratic nations each new generation is a new people.” Roughly 100 years later the social scientist Karl Mannheim similarly observed: “Early impressions tend to coalesce into a natural view of the world.”

The boomers—a generation born into national wealth and power, raised on the promise of their limitless potential and self-worth, reared on television and advertising, enthralled by the wonders of modern science and medicine—are, for all their differences, a most potent emblem of the long American Century.

Even today they remain characteristically unfulfilled. Looking for “more, more, more”—for that “satisfaction” that seems forever to elude them—they will, as they have since 1946, stretch the limits of America’s possibilities and its resources.

In 2046 we’ll still be appraising their work.

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